Evidence indicates that Type II diabetes is increasing rapidly. Ways to improve health and reduce health care costs are needed. The long-term objective of this study is to discover optimal interventions designed to enhance diabetic health through physical activity, and to relate changes in physical activity to changes in lipid metabolism and cardiovascular risk. This will be done with 80 exercise-eligible subjects with a diagnosis of type II diabetes, who are enrolled in a managed-care system. Subjects will be randomly assigned to: (1) A home-based exercise intervention for 12 months, using accelerometer activity monitors with feedback, and with telephoned counseling based on activity data; or (2) An equivalent home-based program without activity monitor feedback to subjects, and telephone counseling based on self-reported exercise. Subjects will receive usual medical care, and will be seen by an endocrinology research fellow who will receive training in behavioral medicine aspects of diabetes. Outcomes will include cardiovascular risk profile (CETP, NEFA, lipids) physical activity, BMI, indicators of diabetic health, and exercise self-efficacy. Analysis of exercise relapse and adherence processes will be done using interview methods.